The average adult has about 6 pounds of skin covering 18 square feet, making skin the body's largest organ. Let's look at how the skin is put together. Skin has three layers. The top layer is the epidermis. It protects the other layers from the outside environment. It contains cells that make keratin, which waterproofs and strengthens the skin. The epidermis also has cells with melanin, the dark pigment that gives skin its color. Other cells in the epidermis allow us to feel touch and provide immunity against invaders like bacteria and other germs.
The bottom layer is the hypodermis. It contains fat cells, or adipose tissue, that insulate the body and help conserve heat.Between the epidermis and hypodermis is the dermis. It contains cells that give skin strength, support, and flexibility.As we age, cells in the dermis lose their strength and flexibility, causing the skin to lose its youthful appearance.
The dermis has sensory receptors that allow the body to receive stimulation from the outside and feel pressure, pain, and temperature.A network of blood vessels provide the skin with nutrients, and remove waste products.
Sebaceous glands produce oil that keeps the skin from drying out. Oil from the sebaceous glands also helps to soften hair and to kill bacteria in the pores of the skin.
These glands cover the whole body, except for the palms of the hands and soles of the feet.
Review Date 7/12/2018
Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.